This background information is provided to reveal information believed by the applicant to be of possible relevance to the present invention. No admission is necessarily intended, nor should be construed, that any of the preceding information constitutes prior art against the present invention.
As electronic devices operate, they may generate heat. This especially holds true with electronic devices that operate by passing an electrical current through a semiconductor. As the amount of current passed through the electronic device may increase, so may the heat generated from the current flow.
In a semiconductor device, if the heat generated from the device is relatively small, i.e., the current passed through the semiconductor is low, the generated heat may be effectively dissipated from the surface area provided by the semiconductor device. However, in applications wherein a higher current is passed through a semiconductor, the heat generated through operation of the semiconductor may be greater than its capacity to dissipate such heat. In these situations, the addition of a cooling device may be required to provide further heat dissipation capacity.
One type of such a semiconductor device may be lamps that utilize light emitting diodes (LEDs). LED lamps may include a plurality of LEDs mounted to a circuit board, where current passes through the LEDs to produce light. The current, however, produces heat in addition to light. Excess heat may decrease efficiency and may, in fact, damage the LEDs. Such damage may include, for example, decreasing efficiency of the LEDs. Heat helps to facilitate movement of dopants through the semiconductor, which may render the LED less powerful, or even useless. There are many ways to dissipate heat, including the use of heat sinks, but enhancing heat dissipation may help to maintain and, in some cases, enhance efficiency of operation of LED lamps.
Two major types of cooling devices exist—active and passive. An active cooling device may require its own power draw to direct heat and heated fluids away from a heat source. A passive cooling device, however, may provide a pathway for heat and heated fluids to be directed away from a heat source. An active cooling device may, for instance, include a fan, while a passive cooling device may, for instance, be provided by a heat sink.
Typically, a heat sink may provide increased surface area from which heat may be dissipated. This increased heat dissipation capacity may allow a semiconductor to operate at a higher electrical current. Traditionally, a heat sink may be enlarged to provide increased heat dissipation capacity. However, increasing power requirements of semiconductor-based electronic systems may still produce more heat than may be dissipated from a connected heat sink alone. Furthermore, continued enlargement of the heat sink size may not be practical for some applications.
Various light effects are desirable when using LED lamp systems. Due to the use of heat sinks, however, light emission may be somewhat limited. In other words, the emission of light from the LED light source may be limited to an upward and/or outward direction. It would be desirable to provide heat dissipating capabilities to an LED that simultaneously decreases limitations on light emission that currently exist.
An additional problem in the prior art is providing light by the operation of a lamp including semiconductor-based lighting elements in more than 180° of direction, i.e., in greater than an imaginary hemisphere either directly above or directly below the light source. Previously, coating the luminaire enclosure with a reflective material has been used to direct light beyond 180° using reflection techniques. Traditionally more than one reflection is needed to direct the light beyond 180°. In doing this, there is often a decrease in efficiency with each reflection.
Other LED luminaires may emit light in more than 180° of direction. Such luminaires, however, typically have cylindrically-mounted LED boards.